If you don't understand it, if it was left as an exercise for the student, if the teacher said he'd cover it Tuesday and Tuesday was the bomb scare, if your dog ate that homework, if the school bully poured soda on those notes, if you skipped a day, if the professor had his non-English-speaking TA give that lecture, or if you haven't the faintest clue what's going on, chances are it'll be on the test.

No wonder so many people hate school and education.